By Kate Devlin

Parkinson’s disease could be diagnosed earlier by measuring changes in the sound of the voice, according to researchers.

In most cases the devastating neurological disease is identified only at an advanced stage, once sufferers have started to show symptoms.

Now researchers in Israel and America have found a way of measuring speech patterns, inaudible to the human ear, to test if apparently healthy people have the condition.

Symptoms of the disease include stiff muscles, tremors and the loss of balance.

However, by the time that patients begin to show these effects their disease is quite advanced and vital brain cells have been significantly damaged.

But researchers have discovered that the voice undergoes changes at earlier stages.

Although they are normally detectable they can be picked up by newly developed computer software.

The team behind the research believe that the method could be used to test people who have the disease in the family, or even to set up a national screening programme.

The condition damages muscles in the neck and mouth, and can give sufferers a husky voice.

But usually these changes are only apparent once the disease has been conventionally diagnosed.

The team behind the study claim that diagnosing patients earlier could prevent the damage of up to 60 per cent of the nerve cells in the area of the brain that controls movement.

They warn that late diagnosis can also mean that the drugs used to treat the condition are less effective.

There are around 120,000 Parkinson’s disease sufferers in Britain and the condition is most common in those over the age of 50.

Prof Shimon Sapir, from the University of Haifa in Israel, who developed the new test, said: “People have tried speech recognition methods previously but they have not really been accurate enough to distinguish between the healthy and those with early Parkinson’s.

“What we have done is to rework the way we analyse speech so that we can accurately use it for diagnosis.”

The findings are published in the Journal of Speech, Language and Hearing Research.

Parkinson’s disease is a progressive neurological condition that destroys the cells that produce the chemical messenger, dopamine, in the part of the brain that controls movement.

Professor Sapir added: ¨What we are trying to do by early detection is to prevent the destruction of those dopamine producing cells.

“Often by the time a patient is normally diagnosed more than half have already been destroyed.”

Dr Kieran Breen, from Parkinson's UK, said: "Trying to find ways to diagnose Parkinson's at an early stage is key to understanding how to develop better and more effective treatments.

“The results of this research show that it may be possible to develop tests to identify subtle voice changes at an early stage of the condition.”

The method was tested on 38 Parkinson’s sufferers and 14 healthy controls.